This invention relates to novel inhibitors of sex steroid activity, for example to steroidal compounds having antagonistic activity on sex steroid receptors. More particularly, the invention relates to certain steroidal compounds having specified side-chains in 17α-position which interact with the androgen receptor, and metabolites thereof which block androgen action by acting, among other mechanisms, through the androgen receptors, while not activating such receptors in some or all androgen-sensitive tissues. Some compounds of the invention are Selective Androgen Receptor Modulators (SARMs) which have desirable antagonist activity in some tissues (e.g. prostate) while exhibiting no activity or desirable agonist activity in other tissues